With growth of people's demand for an ever intelligent lifestyle, demand for high capacity of data processing is also growing. Energy consumption in data processing has reached about hundreds of billions of or even trillions of kilowatts-hour each year, and a large data center can occupy an area up to tens of thousands of square meters. Accordingly, high efficiency and high power density are significant indicators of a health development of the data center industry.
A critical unit of the data center is a server, which is typically equipped with a mainboard composed of data processing chips (such as a CPU, chipsets, a memory or the like), their power supplies and necessary peripheral components. With increase of the processing capacity per volume unit of a server, the number and the integration level of the processing chips are also increasing, resulting in enlargement of occupied space and increase of power consumption. Accordingly, the power supply (also referred to as a mainboard power supply since it is on the same mainboard with the data processing chips) for the chips is excepted to have higher efficiency, higher power density and smaller volume, conducive to the energy saving and reduction of the occupied resource for the entire server or even of the entire data center.
An input power supply provided for digital chip is typically of a low voltage and a large current. In order to reduce a loss due to wiring between the input power supply and the digital chip, the input power supply is required to directly provide supply power for the digital chip. In other words, it is desirable to dispose the input power supply to the digital chip as closely as possible. The input power supplies directly providing supply power for the digital chips are referred to as point of the loads (POL), and the POL are provided supply powers by other power supplies.
Currently, an input voltage of a POL typically is 12V. However, in case where a total power of the server is relatively high and the input voltage of the POL is relatively low, the input current of the POL will be relatively large. For example, if the total power of the server is 1200 W and the input voltage of the POL is 12V, the input current of the POL will be as high as 100 A. The input voltage of the POL is so high that the occupied resource and the loss caused by it on the mainboard become ever more noticeable. If the input voltage of the POL is increased to 48V, for example, the input current of the POL will be reduced significantly, effectively solving the problem of the occupied resource and the loss caused by the input voltage of the POL.
If the input voltage of the POL is 48V, compared with the traditional input voltage of 12V, the value of the voltage is increased by 4 times. Although the POL having the traditional input voltage of 12V is typically implemented with a BUCK circuit, it is difficult to implement the POL having the input voltage of 48V with a BUCK circuit since the duty cycle is too small. In order to solve the above problem, in the related art, a power supply configuration is proposed as shown in FIG. 1. In FIG. 1, an input terminal of a data processing mainboard 1 is connected in parallel to an input voltage Vin. The input voltage Vin is an input voltage Vin of the data processing mainboard 1, which is 48V. Converters 48V-Vo1, 48V-Vo2 and 48V-Von each receives the input voltage Vin, converts the input voltage Vin to a respective output voltage, and provide it for a corresponding load (a load 1, a load 2 and a load n as shown in FIG. 1).
The converters 48V-Vo1, 48V-Vo2 and 48V-Von in FIG. 1 each can be simply implemented with a single-stage isolation converter. FIG. 2 shows a circuit diagram of the converter in FIG. 1. An input voltage of 48V (48V+ and 48V− as shown in the figure) is converted by the single-stage isolation converter to be output an output voltage Vo (VO+ and VO− as shown in the figure) for the load. The single-stage isolation converter can be a pulse width modulation (PWM) converter such as a forward converter/a flyback converter, or can also be a pulse frequency modulation resonant converter such as a LLC/LC/LCL or the like.
Since the digital chip such as the CPU has a wide range of operating voltage, the single-stage isolation converter typically achieves both of the critical indicators of wide operating range and isolation at the expense of efficiency and power density. In addition, the single-stage isolation converter having the input voltage of 48V is of a relatively complex configuration. Also, the single-stage isolation converter having the input voltage of 48V has a limited power if it directly supplies power to a single load, and thus is not suitable for parallel multiplex to achieve reduced capacitor volume and improved light load efficiency. Accordingly, it is hardly possible for the single-stage isolation converter having the input voltage of 48V to meet the future demand.